The present invention relates to a device for the detection and characterizing of radar pulses and notably of monopulse secondary radar pulses.
In monopulse secondary radars, the pulse has to meet a certain number of criteria related to duration and level in order to be considered as forming part of a message. The duration is assessed, for example, to reject those pulses that do not meet the characteristics of an IFF (Identification Friend or Foe) pulse. The decoding is done by assessing the spacing between the pulses that constitute the message, the pulses of one and the same message having comparable levels. The relative level of the pulses with respect to one another enables the pulses received to be associated with a given message. Since it happens that pulses forming part of different messages may overlap and prompt confusion in the decoding of the messages, the device for the detection of monopulse radars is responsible for separating the overlapping pulses and characterizing them in terms of width and level. The detection device also takes account of the different types of scrambling in order to minimize their effects on the detection of pulses.
In the prior art, the detection of pulses takes place in an analog manner. It consists in eliminating the continuous component of the signal and in making a detection of pulse edges by a shift of the level of the incident signal and by comparison after storage of the result with a predetermined threshold value. Unfortunately, the behavior under AMCW (Amplitude Modulation Continuous Wave) type scrambling notably of the corresponding pulse detectors is poor. Moreover, the performance characteristics of the message decoders undergo substantial deterioration through pulse scrambling, all the more so as these devices carry out practically no treatment on the pulses. Finally, the detection rate remains small for a low signal-to-noise ratio (8 to 10 dB).